The present invention relates to information reproducing apparatuses such as a CD (Compact Disc) player, and more specifically, to an information reproducing apparatus capable of reproducing information recorded in different kinds of information storage media in a compatible manner, and an information reproducing method therefor.
The CD for reproduction only (hereinafter as xe2x80x9cCD-ROMxe2x80x9d) was developed as an information recording medium capable of recording a large amount of information in a high density. More recently, the CD to which information can be additionally recorded (hereinafter as xe2x80x9cCD-Rxe2x80x9d) was developed.
The CD-ROM is an information recording medium only for reproduction (read only), while the CD-R can be recorded with additional information though already recorded information cannot be deleted therefrom. The CD-R therefore provides diversity as an information recording medium.
The CD-R was developed as an information recording medium compatible with the CD-ROM. An information reproducing apparatus adapted only for the CD-ROM specification can also reproduce information recorded in the CD-R.
FIG. 10 shows the data structure of a CD-ROM, while FIGS. 11 to 13 show the data structure of a CD-R.
In FIG. 10, the CD-ROM includes a lead in area LIA, a program area PA, and a lead out area LOA from the inner circumferential side to the outer circumferential side. The program area PA is a recorded area which is recorded with contents information such as music information. The lead out area LOA is recorded with information indicating an end position of the program area PA.
These lead in area LIA, program area PA, and lead out area LOA are generically referred to as information area, and recorded with information after EFM modulation (Eight to Fourteen Modulation).
The lead in area LIA is recorded with index information called TOC (Table of Contents), i.e., index information such as the total number of music recorded in the program area PA, the total recording time, the recording start position (recording start address), and the recording end position (recording end address).
The program area PA is recorded with the contents information on a frame-basis, and each frame is attached with information called sub coding.
More specifically, one set of sub coding information for 98 frames is specified to have one meaning. When reproducing time per frame is xcfx84, one set of sub coding information can be read out for each time period of 98xc3x97xcfx84.
The sub coding information includes information for eight channels P, Q, R, S, T, U, V and W. The channel P represents a silent part inserted between music in for example music information. The six channels R, S, T, U, V and W are used to record information on characters used for a karaoke (sing-along system) display.
The channel Q is for recording information such as movement numbers in the music information as described above, index numbers in a movement, the passed time in a movement at a frame position in a music and absolute time. The information reproducing apparatus reproduces the Q channel information, so that the track numbers, the passed time in the music being presently reproduced or absolute time can be displayed in real time.
In FIG. 11, if the CD-R has never been recorded with contents information, there is no information recorded in areas corresponding to the lead in area LIA, the program area PA and the lead out area LOA, in other words, a so-called unrecorded area URA is formed. The CD-R is typically provided with a power calibration area PCA on the inner circumferential side for test writing at the time of recording information. The power calibration area PCA is also entirely new in this case.
A CD-R after at least one information recording and still having an unrecorded area URA is called partially recorded disc (partial disc). The data structure of such a partial disc is shown in FIG. 12.
More specifically, music information or the like is recorded to the disc to form a program area PA and a program memory area PMA. The program area PA is formed by recording the music information or the like in a part of the unrecorded area URA. The program memory area PMA is formed by recording information related to the history of the music information or the like recorded in the program area PA.
The information related to the history is called xe2x80x9ctemporary TOCxe2x80x9d and includes information on the recording start position (recording start address) and the recording end position (recording end address) of information recorded in the program area PA.
When an information reproducing apparatus adapted for the CD-R specification reproduces information from this partial disc (hereinafter as xe2x80x9cpartial CD-Rxe2x80x9d), the apparatus can read the temporary TOC information and access music information or the like recorded in the program memory area PMA for reproduction based on the read temporary TOC information. When information is additionally recorded in the unrecorded area URA of the partial CD-R, access is controlled based on the temporary TOC information, so that the information can be additionally recorded from the start position of the unrecorded area URA.
Note however that the information reproducing apparatus adapted for the CD specification accesses information recorded in the program area PA based on the TOC information in the lead in area LIA as shown in FIG. 10. Therefore, the apparatus is not adapted to read the temporary TOC information. More specifically, the pickup cannot move to the PMA area. As a result, information recorded in the program area PA in the partial CD-R cannot correctly be accessed for reproduction.
FIG. 13 shows the structure of data in a partial CD-R after finalization processing, i.e., the data structure in a partial CD-R finalized such that the information reproducing apparatus adapted for the CD-ROM specification can correctly reproduce information.
When the information reproducing apparatus adapted for the CD-R specification performs the finalization processing as described above, TOC information is produced based on the temporary TOC information recorded in the program memory area PMA in the partial CD-R. Then, the TOC information is recorded in an empty area URLIA (see FIG. 12) between the program memory area PMA and the program area PA, so that a lead in area LIA identical to that in the CD-ROM can be formed. Also, information indicating the end position of the program area PA is recorded in an unrecorded area at the rear of the program area PA, so that a lead out area LOA can be formed.
As described above, the TOC information and the like adapted for the CD-ROM specification can be recorded in the lead in area LIA and lead out area LOA by the finalization processing. As a result, the information reproducing apparatus adapted only for the CD-ROM specification can reproduce information from a CD-R similarly to a CD-ROM.
As described above, the conventional information reproducing apparatus adapted only for the CD-ROM specification cannot read the temporary TOC information, and therefore information cannot correctly be reproduced from the partial CD-R.
The parietal CD-R however advantageously permits information to be additionally recorded in an unrecorded area until the disc is finalized. Therefore, there has been an increasing demand for an information reproducing apparatus adapted only for the CD-ROM specification and yet capable of reproducing information from the partial CD-R correctly.
The conventional information reproducing apparatus adapted only for the CD-ROM specification cannot correctly reproduce information from a partial CD-R for the following reasons.
In the conventional information reproducing apparatus adapted to reproduce only from the CD-ROM, the pickup cannot physically move to the PMA area present more on the inner circumferential side than the LIA area. Therefore, the apparatus cannot read xe2x80x9ctemporary TOC,xe2x80x9d and information such as the total number of music, the total recording time and the recording end position cannot be detected.
The conventional information reproducing apparatus can only cope with the spindle servo method according to which the linear velocity is constant based on the velocity information extracted from an EFM modulated signal in read information. Therefore, only the recorded part can normally be reproduced. If the pickup is moved to an unrecorded part for reproduction, the rotation could be out of control. In such a case, the pickup must be moved to a recorded part so that the rotation may be controlled stably.
For these restrictions associated with reproduction of the partial CD-R using the conventional information reproducing apparatus, convenient functions enabled using the disc such as track search, program reproduction and random reproduction can hardly be achieved.
The track search is a function to select and reproduce a desired music from the total number of music. The program reproduction is a function to program desired music selected from the total number of music in a sequence for reproduction. The random reproduction is a function to randomly select music from the total number of music on the reproducing apparatus side for reproduction.
In a track search operation, if the total number of music and the recording end address are not available, the pickup must always be moved little by little for fear that the pickup enters an unrecorded area, which increases time for accessing. The program reproduction or random reproduction operation can hardly be achieved if the total number of music is not known.
Note that the following method might be employed in order to avoid these problems. All the information from the recording start position to the recording end position of the program area PA is reproduced. Then, in initialization, the physical position where the RF signal ceases to be obtained is determined as the start position (absolute address) of the unrecorded area URA. After the initialization, access is controlled so as not to go beyond the determined absolute address.
This method however necessitates all the recording tracks having pits to be line-scanned and the initialization takes too long. Therefore, the method is disadvantageously inconvenient for the user.
If the initialization is performed by line-scanning, a damage encountered in the process could cause a track jump to the inner circumference; in other words, the operation might come into a loop state and never end in some cases.
The present invention is directed to a solution to these disadvantages associated with the conventional technique, and it is an object of the present invention to provide an information reproducing apparatus capable of reproducing information recorded in different types of information recording media in a compatible manner, and an information reproducing method therefor.
More specifically, it is an object of the present invention to provide an information reproducing apparatus capable of quickly detecting the recording end position of a program area in a partial CD-R and an information reproducing method therefor.
In order to achieve the above objects, an information reproducing apparatus according to present invention has a pickup for detecting physical information on opposing positions in a disc-shaped information recording medium including a recorded area having a recording track recorded with information and an unrecorded area with no information record to output a detection signal, and generation means for generating the information recorded in the recorded area based on the detection signal. The recorded area and unrecorded area are present in series. The apparatus includes moving means for advancing/withdrawing the pickup in the radial direction of the information recording medium, signal generation means for generating a feature signal including physical feature information on the information recording medium in the radial direction based on the detection signal output from the pickup during the radial movement, determination means for determining which area the pickup has detected physical information on, the recorded area or the unrecorded area, based on a change in the feature signal, and control means for controlling each operation of the moving means, the signal generation means and the determination means while determining an end position of the recorded area based on a determination result by the determination means.
An information reproducing method in an information reproducing apparatus having a pickup for detecting physical information on opposing positions in a disc-shaped information recording medium including a recorded area having a recording track recorded with information and an unrecorded area with no information recorded to output a detection signal, and generation means for generating the information recorded in the recorded area based on the detection signal. The recorded area and the unrecorded area are present in series. The method includes a first step of advancing/withdrawing the pickup in the radial direction of the information recording medium, a second step of generating a feature signal including physical feature information on the information recording medium in the radial direction based on the detection signal output from the pickup during the radial movement, a third step of determining which area the pickup detects physical information on, the recorded area or the unrecorded area, based on a change in the feature signal, and a fourth step of determining the end position of the recorded area based on the determination result.
According to the information reproducing apparatus and the information reproducing method in the information reproducing apparatus, the pickup is moved in the radial direction of an information recording medium, and the end position of the recorded area in the information recording medium is detected based on a feature signal in the radial direction obtained during the movement. Thus, the end position of the recorded area can be detected faster than the method of line-scanning all the information in the recorded area. The accessing inability encountered by the conventional techniques can be avoided and information can correctly be reproduced from the recorded area.